Add CHANGELOG.md entries

Verbose description:
* Fix 'iloc' box parsing when offset_size, length_size or
  base_offset_size was equal to 1 or 2. Such rare files were wrongly
  accepted.
* Fix 'iloc'v1/2 box parsing when base_offset_size!=0. Such rare files
  were wrongly rejected.
* Fix 'iloc'v1/2 box parsing when index_size!=0. Such rare files were
  parsed with corrupted extent offsets and sizes instead of ignoring
  index_size.

CHANGELOG.md

@@ -91,6 +91,9 @@ The changes are relative to the previous release, unless the baseline is specifi
   (https://crbug.com/oss-fuzz/65657).
 * ext/libjpeg.cmd now pulls libjpeg-turbo instead of libjpeg and AVIF_JPEG=LOCAL
   now expects the library dependency in ext/libjpeg-turbo/build.libavif.
+* Fix 'iloc' box parsing bugs that may have wrongly accepted, rejected or parsed
+  some files with rare values of offset_size, length_size, base_offset_size and 
+  index_size.
 
 ## [1.0.4] - 2024-02-08